1. Field of the Invention (Technical Field)
The present invention relates to displays and more particularly to a method and apparatus for implementing pixels in a two or three dimensional volume and to provide individual pixel intelligence.
2. Background Art
Modern digital display devices commonly employ a two dimensional (2-D) array of pixel elements arranged in columns and rows. Each pixel typically contains a red, a green, and a blue element. Each sub-pixel or element is connected to one corresponding row wire trace and one column wire trace on the supporting substrate as shown in FIG. 1.
For a typical M×N pixel display, the image is constructed by first loading each of the 3N column drivers with a separate digital value corresponding to the color amplitude of the sub-pixel for the first row. Then 3N Digital-to-Analog converters transform these digital values to a corresponding analog voltage for each sub-pixel. Column wire traces route this signal to every sub-pixel in that column. After the analog data is ready, the first row wire is momentarily set to an enable state that causes only the sub-pixels in the first row to sample their input value while the other rows ignore the input. When thus enabled, the circuitry in each sub-pixel captures and holds the sub-pixel display value. Each sub-pixel is designed to transform the applied analog voltage to a visible display appearance. After row 1 is thus activated, the process repeats for row 2, then row 3 etc. The fill order, or even the roles of the rows and columns, may be reversed by the designer. In this way, two 1-dimensional arrays of control wires are used to drive a 2-D display.
The 2-D display described above can also be extended to 3-dimensions (3D) in at least two ways: 1) layering the 2D displays; or 2) true 3D fabrication. In either case, three 1-dimensional arrays are used to control the 3-dimensional display. FIG. 2 shows an implementation of a 3-D display of M×N×J pixels using layered 2-D displays. Each plane can be filled either in parallel or sequentially from the signal source. In a sequential implementation, the rastor scan is a 1-dimensional “row” (whose “columns” data is loaded in parallel for a single plane). The rastor scan steps through a 2-D pattern, first covering rows 1-M and then repeating to cover layers 1 through J. If the implementation allows all J layers to be loaded in parallel, the output scan shape becomes in effect, a plane that steps through a 1-D pattern to cover all “row” wireplanes in parallel.
FIG. 3 shows a more truly 3-D (more symmetric) implementation of a 3-D display with M×N×J pixels. In this case each 1 dimensional control array output signal is routed in two (2) dimensions to all subpixels in a plane. The three control arrays correspond to three orthogonal wireplanes that collectively can uniquely address each pixel. The scan shape for this display is a 1-D line of pixels (tied to the XZ wireplane driver array in FIG. 3) that must step through a 2-D scan pattern to render the 3-D display.
Such 2-D displays utilize complex two-dimensional mechanical structures normally consisting of substrates or superstrates with two or more individual electrical signal lines connected to each pixel to carry the image signal that is to be displayed. Implementing pixels in a 3-D volume is even more problematic, requiring a 3-D mechanical structure. Each of these structures consists of a multitude of microscopic elements fabricated within a relatively macroscopic matrix structure, which poses a difficult problem for fabrication and with inherent fragility that limits reliability of fabrication and operation.
The nature of the matrix also requires a complex external mechanism be used to first create the signal image as a whole and then decompose it into individual signals to be routed to each sub-pixel in sequence. In so doing, the matrix mechanism limits how the pixels can be controlled: Pixels must take turns with only one row for 2D or true 3D displays or one plane for layered 3D displays receiving a signal at any time. Because of this approach, the display update rates are limited by the time it takes to propagate the raster “scan shape” down one row or plane at a time in order to refresh all pixels.
The above-mentioned problems with conventional displays are inherent in most or all current mass-produced displays. The cost of fabricating the conventional display limits low-end display cost. The complexity and fragility of the fabricated display ensures that most displays will develop, when manufactured or subsequently during operation, one or more pixels that are defective and reduces the perfection of the display image.
Building larger displays can be approximated in some situations by using multiple independent smaller display assemblies. This can increase production yield, but does not reduce significantly the manufacturing precision requirements or fragility problems.
The display industry has spent decades solving these difficult manufacturing problems in order to manufacture higher resolution, larger displays with microscopic pixel elements embedded in a macroscopic matrix with sufficient repeatability to produce modestly priced, modestly reliable displays of a limited size.
For general purpose imaging displays, all manufacturers' design solutions seem to be similar. All solutions are aimed at meeting the challenge of performing the difficult mechanical fabrication as well as possible.
Some prior art references attempt to solve some of the problems raised above, but fail to accomplish a solution as disclosed in this patent application. These include U.S. Pat. No. 5,838,337, entitled “Graphic system including a plurality of one chip semiconductor integrated circuit devices for displaying pixel data on a graphic display” which teaches a method for storing graphic data and a circuit using the method which enables a higher-speed execution of dyadic and arithmetic operations on graphic data with a memory circuit which performs read, modify, and write operations in a write cycle so that the number of dynamic steps is greatly reduced in the software section of the graphic processing. This method supports a display device having a graphic display area, which includes a plurality of display portions and a plurality of one-chip semiconductor integrated circuit devices. Another prior art device is disclosed in U.S. Pat. No. 5,900,850 entitled “Portable large scale image display system”. This device is a large scale, portable light emitting diode image display system including one or more display panels comprising a web or netlike structure, preferably formed of interconnected flexible foldable strap members arranged in plural vertical columns and horizontal rows. Yet another prior art device is disclosed in U.S. Pat. No. 6,237,290 entitled “High-rise building with large-scale display device inside transparent glass exterior”. This invention is a high-rise building with a large-scale display device on its exterior consisting of a large scale display device which can be constructed inside the transparent glass exterior by installing multiple modules in rows and columns.
Because of their dependence on a row/column structure, the prior art approaches have similar problems for rendering a large display in a 3-D volume or 2-D displays in a non-rectangular shape. These problems include that prior art displays are very complex mechanically and require expensive, highly engineered manufacturing tooling and processes to produce acceptable yields for large displays and production of displays much larger than those currently available are desirable, but made costly or impractical by yield limitations as display resolution increases.
A number of undesirable design and manufacturing constraints are inherent to current techniques. These include:
a) precision manufacturing of microscopic elements in a macroscopic structure;
b) making pixels part of a large physically-monolithic matrix makes bad pixels in displays difficult to repair;
c) use of row-column encoding in the matrix to get the activation signal to each pixel means that the rest of the display is inaccessible while each raster set of the pixels is receiving its value. Such a display cannot directly accept stroke inputs or multiple inputs; and tends to have a lower maximum refresh rate.
d) it is difficult to flexibly omit portions of rows or columns in order to make a display that is not rectangular in shape.
Further, using the prior art techniques to implement pixels in a 3-D volume would require several extraneous elements, such as row, column wiring and potentially layer wiring to each pixel, row and column decoding circuits, and drivers that are located outside of the pixels themselves, and additional software and memory resources added to the image generator to support mixing signals from multiple sources.
There are no known displays that replace one or more of the wires routed individually to each pixel row or sub-pixel column with a signal that is available from a single source in common to all pixels or use internal pixel controls as provided in the present invention.